Original Article
Copyright ©2012 Baishideng Publishing Group Co., Limited. All rights reserved.
World J Gastroenterol. Jul 28, 2012; 18(28): 3681-3695
Published online Jul 28, 2012. doi: 10.3748/wjg.v18.i28.3681
Study of human B7 homolog 1 expression in patients with hepatitis B virus infection
Wen-Jin Zhang, Hai-Yang Xie, Xin Duan, Yun-Le Wan, Chuan-Hui Peng, Shao-Hua Shi, Rong Su, Zhang-Hui Zheng, Le-Lin Pan, Lin Zhou, Shu-Sen Zheng
Wen-Jin Zhang, Xin Duan, Yun-Le Wan, Chuan-Hui Peng, Shao-Hua Shi, Le-Lin Pan, Shu-Sen Zheng, Division of Hepatobiliary and Pancreatic Surgery, Department of Surgery, First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310003, Zhejiang Province, China
Hai-Yang Xie, Rong Su, Zhang-Hui Zheng, Lin Zhou, Key Laboratory of Combined Multi-organ Transplantation, Ministry of Public Health, Hangzhou 310003, Zhejiang Province, China
Yun-Le Wan, Department of Hepatobiliary Surgery, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou 510120, Guangdong Province, China
Author contributions: Zhang WJ contributed designed the research and wrote the paper; Zheng SS contributed to research design; Xie HY and Duan X contributed to the pathology experiments; Peng CH and Su R contributed to the real time polymerase chain reaction experiments; Zheng ZH contributed to the flow cytometry experiments; Pan LL and Zhou L contributed to specimen collection; and Wan YL and Shi SH contributed to data analysis.
Supported by Key Program of National Natural Science Foundation of China, No. 30730085; Zhejiang Provincial Natural Science Foundation, No. Y2110169; Zhejiang Provincial Natural Science Foundation, No. Y207465
Correspondence to: Shu-Sen Zheng, MD, PhD, FACS, Division of Hepatobiliary and Pancreatic Surgery, Department of Surgery, First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310003, Zhejiang Province, China. shusenzheng@zju.edu.cn
Telephone: +86-571-87236466 Fax: +86-571-87236884
Received: October 12, 2011
Revised: March 28, 2012
Accepted: April 12, 2012
Published online: July 28, 2012
Abstract

AIM: To further investigate the role of human B7 homolog 1 (B7-H1) in the mechanism of persistent hepatitis B virus (HBV) infection.

METHODS: Peripheral and intra-hepatic B7-H1 expression were compared by flow cytometry and immunochemical staining between two 2 distinct groups, one being chronic HBV tolerance patients (CHB-T) and the other being acute hepatitis B patients (AHB). B7-H1 mRNA expression level was also compared by real time polymerase chain reaction between CHB-T and AHB patients. The location of intra-hepatic B7-H1 and CD40 expression were analyzed by immunofluorescence. The levels of B7-H1 and CD40 expression on cultured myeloid dendritic cells (mDCs) with or without hepatitis B surface antigen (HBsAg) treatment were analyzed dynamically by flow cytometry. Intracellular interferon-γ (IFN-γ) staining and the stimulatory capacity of mDC of cultured mDC with or without HBsAg treatment were also compared by flow cytometry.

RESULTS: Peripheral B7-H1 expression on mDCs was increased significantly in AHB compared to CHB-T patients (P < 0.05). In the liver tissues from CHB-T patients, B7-H1 positive cells were almost absent despite a persistently elevated serum HBsAg load. In contrast, there were indeed increased B7-H1-positive cells in situ in the liver tissue from AHB. In vitro analysis showed the parallel upregulation of B7-H1 and CD40 on CD11c+ mDCs after the onset of stimulation. Addition of recombinant hepatitis B surface antigen (rHBsAg) significantly decreased CD40 expression (P < 0.05 at 16 h, 20 h and 24 h time points). B7-H1 expression was also inhibited by rHBsAg, and the inhibition rate of CD40 was greater than that of B7-H1. This preferential inhibition of CD40 expression on mDCs by rHBsAg resulted in the dysfunction of mDCs and T cells in the mixed leucocyte reaction (MLR) system. With rHBsAg pretreatment, in a carboxyfluorescein diacetate succinimidyl ester (CFSE) labeled MLR system at a ratio of 1:5 responder cell-stimulator cell (R/S), the CFSEdim percentage of T cells decreased from 85.1% to 25.4% and decreased from 30.3% to 12.0% at 1:10 R/S. IFN-γ production by CD8+ T cells, in the MLR system, was reduced significantly by HBsAg pretreatment. At ratios of 1:5 R/S, the percentage of IFN-γ and CD8 dual positive T cells decreased from 55.2% ± 5.3% to 15.1% ± 3.1% (P < 0.001), and decreased from 35.0% ± 5.1% to 7.3% ± 2.7% at ratios of 1:10 R/S (P < 0.001).

CONCLUSION: B7-H1 is not a signature of immune dysfunction, but an inflammation marker. HBsAg regulate immune response by tipping the balance between B7-H1 and CD40.

Keywords: Hepatitis B virus; Hepatitis B; Human B7 homolog 1; Immune tolerance; Co-stimulatory molecule